There is known a control apparatus for an electric vehicle provided with an electric motor serving as a drive power source, and a step-variable transmission, where the control apparatus is configured to shift-down the step-variable transmission on the basis of a shift-down initiating condition set on the basis of a running speed of the vehicle and an amount of regeneration of an electric energy by the electric motor during regenerative deceleration of the vehicle in which the electric motor is placed in a regenerative state. WO2010/137123 discloses an example of such a control apparatus. The vehicle disclosed in WO2010/137123 is provided with: an electrically controlled differential portion having a planetary gear set, a first electric motor (differential electric motor) connected to a sun gear of the planetary gear set, and a second electric motor (vehicle driving electric motor) connected to a ring gear of the planetary gear set; and a step-variable automatic transmission portion which is connected to an output rotary member (ring gear) of the electrically controlled differential portion and which is shifted with engaging and releasing actions of coupling elements. This vehicle is arranged such that operating state of the first electric motor is controlled to control a difference between input and output speeds of the planetary gear set, namely, a rotating speed of its input rotary member in the form of a carrier provided to receive a rotary motion of the engine, and a rotating speed of its output rotary member in the form of the ring gear. The vehicle control apparatus of WO2010/137123 is configured to implement a coasting shift-down action of the step-variable automatic transmission portion followed by a regenerative operation of the second electric motor, which coasting shift-down action takes place during a coasting run of the vehicle with its accelerator pedal kept in its non-operated or fully released position. The vehicle control apparatus makes a determination as to whether the coasting shift-down action should be implemented or not, on the basis of a coasting shift-down boundary line of the vehicle speed, which is formulated as a range of coasting shift-down points and such that the vehicle speed above which the coasting shift-down action is implemented increases with an increase of an amount of electric energy regenerated by the second electric motor. This vehicle control apparatus permits the second electric motor to be operated at a relatively high speed in a relatively high region of its regenerative torque, whereby a power loss of the second electric motor during its regenerative operation is reduced, so that power recovery efficiency of the vehicle is improved.
By the way, during regenerative operation of an electric motor in a high region of its regenerative torque during a decelerating run of the vehicle, it is difficult to accurately synchronize operating speed of the motor while controlling the electric motor so as to maintain a desired regenerative braking force upon a shift-down action of the step-variable automatic transmission portion. Accordingly, longitudinal acceleration of the vehicle tends to considerably vary, due to a variation of the regenerative braking force. The vehicle operator tends to feel a higher degree of a shift shock of the step-variable automatic transmission portion in a second control mode (automatic control mode) of the vehicle in which acceleration and deceleration (braking) of the vehicle are automatically adjusted, not depending upon operations by the vehicle operator to accelerate and decelerate (brake) the vehicle, than in a first control mode (manual control mode) of the vehicle in which the vehicle is accelerated and decelerated on the basis of the accelerating and decelerating operations by the vehicle operator, so as to reflect the desire of the vehicle operator. Examples of the second control mode include an auto-cruise control mode; a preceding-vehicle tracing control mode; and a fully automatic vehicle control mode in which acceleration, deceleration (braking) and steering of the vehicle are automatically adjusted not depending upon operations by the vehicle operator. As a result, the vehicle operator may feel a discomfort with the shift-down shock caused by the variation of the longitudinal acceleration of the vehicle upon the shift-down action of the step-variable automatic transmission portion during a regenerative decelerating run of the vehicle in the second control mode in which the vehicle acceleration and deceleration are automatically adjusted not depending upon the vehicle operator's operations.